As for a roller conveyor using driven rollers, there is a construction as found in, e.g., U.S. Pat. No. 5,080,219. This prior art construction comprises a roller shaft supported in a frame, a freely rotatable roller fitted on said roller shaft, a flexible body attached to said roller shaft and adapted to be expanded and contracted for contact with and separation from the inner surface of said roller body, a fluid feed and delivery passage which opens to the interior of said flexible body through said roller shaft, and a driven section provided on said roller shaft.
According to this prior art construction, torque is imparted to the driven section, whereby the flexible body is integrally rotated. In this state, fluid is fed to the flexible body through the fluid feed and delivery passage so as to expand the flexible body by the fluid pressure until it abuts (or presses) against the inner surface of the roller body, thereby integrally rotating the roller body to convey articles. When the pressure in the flexible body is released through the fluid feed and delivery passage, the flexible body is contracted to separate from the inner surface of the roller body, whereupon the torque transmission to the roller body is interrupted; thus, the rotation of the roller body is stopped.
In the case of the prior type described above, however, when the flexible body is contracted to separate from the inner surface of the roller body, the roller body does not stop but continues rotating owing to the frictional resistance of the bearings and inertial force. Therefore, when the roller body supports articles to be conveyed which are light in weight, it continues conveying them.